Lesson 02 of 05

An edit nobody would notice by eye

Edit the agreement as lightly as you like. The page recomputes SHA-256 and shows exactly how this example changes.

Make an edit

The documentedit it freely
Its fingerprintrecomputed on every keystroke

Before your edit

Computing fingerprint…

After your editchanged characters in amber

Computing fingerprint…

Both fingerprints are computed in this browser from the text as you left it.

Computing the comparison…

Computing fingerprint…

Measure the change

The one-space edit and the replacement document both produce fingerprints that look unrelated to the original. The exact counts are computed, not written in advance, and they are not a measure of how similar the documents are.

Why it matters

A verifier compares the complete fingerprint for equality. There is no useful partial match or “close enough” score: a mismatch means the retained bytes did not reproduce the recorded digest under the same processing rule.

Technical version

SHA-256 is designed so a small input change produces a widely changed output. The exact number of changed bits or hexadecimal characters varies, which is why this page computes the counts. Different inputs can share a digest in principle; the comparison is strong cryptographic evidence, not mathematical certainty.